Abstract : In this paper the authors discuss the effects of particles fillers mixed in a composite polymer on the space charge measurement techniques. The origin of particle-induced spurious signals is determined and silica filled epoxy resin is analysed by using the laser-induced-pressure-pulse LIPP, the pulsed-electroacoustic PEA and the laser-induced-thermal-pulse LITP methods. A spurious signal identified as the consequence of a piezoelectric effect of some silica particles is visible for all the methods. Moreover, space charges are clearly detected at the epoxy-silica interface after a 10-kV-mm poling at room temperature for 2 hours.